The present invention relates to a centrifugal mill for laboratory use with a rotor as a milling tool coupled to a drive motor. An annular sieve encloses the milling chamber of the rotor and an annular receptacle is arranged at the outer circumference of the annular sieve for receiving the milled material, whereby the milling unit comprised of rotor, annular sieve and milling arrangement is closable with a housing cover that has an inlet opening for feeding the material into the mill.
A centrifugal mill with the aforementioned features is disclosed in the brochure of the firm RETSCH GmbH & Co. KG, Haan, Germany, published under the title "Ultra-Zentrifugalmuhle Typ ZM 1" (page 27). The known centrifugal mill comprises a rotor as a milling tool which is surrounded by a cup-shaped housing part and slipped onto an upright drive shaft of the motor. It is fastened to the drive shaft with a screw. The milling chamber in which the rotor rotates is surrounded by an annular sieve which is surrounded by an annular receptacle so that the material that has been milled by the rotor rotating at high rotational speeds is forced by centrifugal forces through the annular sieve into the annular receptacle. The thus formed milling unit is closed by a cover to be connected to the housing.
The known centrifugal mill has the disadvantage that the inner side of the housing cover in the area which covers the rotor, respectively, the milling chamber must be considered part of the milling chamber so that upon opening of the housing cover milled material maybe lost. Accordingly, corresponding imprecisions of the analyses of the milled material cannot be prevented. As a further disadvantage it should be mentioned that the cleaning of the known centrifugal mill is very complicated. After opening the cover, the annular sieve and the annular receptacle must be removed one after another from the housing and since these parts are separate components, these parts must be individually cleaned. Furthermore, during the corresponding manipulation of the parts material may again be lost. Finally, it is difficult and cumbersome to exchange the rotor because the screw for connecting the rotor to the drive shaft must be removed with a tool, respectively, must again be tightened with a tool.
It is therefore an object of the present invention to provide a centrifugal mill of the aforementioned kind the manipulation of which is considerably facilitated.